1. Artificial Pacemakers and Anesthesia
Presentors:
Dr. Abraham Sonny
Dr. Bala Chandran
Moderator:
Dr. Rashmi Ramachandran

2. Components
Lead : insulated wire that extends from the generator to the electrode
Pulse generator : contains the electric circuit and energy supply
Electrode : the metal portion of lead in direct contact with myocardium

3. Lead Unipolar (positive on skin and negative in myocardium)
Bipolar (both in heart)
Can be either endocardial or epicardial
More than 1 lead present in multisite pacing

4. Unipolar

5. Bipolar

6. Electrode Has both stimulating as well as sensing functions
Steroid eluting electrode

7. Pacing threshold - strength duration curve
Always expressed in terms of voltage and pulse duration

8. Ventricular stimulation (capture)
Output pulse of the pacemaker
Voltage and pulse duration

9. Sensing
Function of pacemaker by which it senses the intrinsic electrical activity of the heart
It identifies this electrical activity by identifying the QRS complex or the R wave in the ECG.

10. Sensing
The pacemaker has to correctly recognize the R wave and distinguish it from ambient electrical disturbances as well as from own T wave
Slew rate: Rate of change in signal amplitude with time

11. Sensing circuit

12. Terminology
Escape interval: Time the generator takes to emit an impulse in absence of R wave
Automatic interval : Time (in msec) between successive pacemaker impulses
Hysteresis : difference between escape and automatic intervals
Pacemaker ventricular refractory period

13. What is pacemaker ventricular refractory period ?
Occurs after both after paced as well as sensed beat

14. Pacemaker nomenclature
Position I
(pacing chamber)
O- none
A- atrium
V- ventricle
D- dual (atrium and ventricle)
Position II
(sensing chamber)
O- none
A- atrium
V- ventricle
D- dual (atrium and ventricle)

15. Pacemaker nomenclature
Position III
(response to sensing)
O – none
I- inhibited
T- triggered
D- dual
Position IV
(programmability)
O- none
R- rate modulation

16. Pacemaker nomenclature
Position V
(anti-tachycardia function)
O- none
P- pace
S- shock
D- dual (pace and shock)

17. Asynchronous ventricular pacing (VOO)

18. VVI

19. AAI

20. DDD

21. Methods of rate adaptive pacing (primary sensors)
Physiological sensors that detect the primary determinants of sinoatrial node function
(circulating catecholamines and ANS activity)

22. Methods of rate adaptive pacing (secondary sensors)
Respiratory rate and minute ventilation (impedance)
QT interval shortening
Oxygen saturation
Central venous temperature rise
Increase in RV stroke volume
Decrease in venous blood PH

23. Methods of rate adaptive pacing (tertiary sensors)
Body movement (vibration)
Body movement (acceleration)

24. Disorders of conducting system
SA node dysfunction
AV conduction disturbances
Bundle branch block

26. First degree heart block
PR interval more than 0.2 s.
Every P wave followed by QRS complex.

28. Second degree heartblock – Mobitz type I (Wenckebach)
Progressive lengthening of PR interval
Followed by one non conducted beat
Next conducted beat has a shorter PR than preceding beat.

30. Second degree heartblock – Mobitz type II
PR interval of conducted beat is constant
One P wave is not followed by a QRS complex

32. Third degree heart block
No temporal relationship between Pwave and QRS complexes
Broad QRS complexes

34. Right bundle branch block
Normal cardiac axis
Wide QRS
RSR1 pattern in V1 and deep wide S wave in V6

36. Left bundle branch block
Normal axis
Wide QRS
M pattern in leads I, VL, V5, V6

37. Left anterior hemiblock
Wide QRS complex
Left axis deviation

39. Presence of RBBB along with left hemiblock
Bifascicular block
Presence of RBBB along with left hemiblock

40. RBBB and left anterior and posterior hemiblock
Trifascicular block
RBBB and left anterior and posterior hemiblock

41. Indications for artificial cardiac pacing
AV conduction abnormalities
Sinus node dysfunction
Neurocardiogenic syncope
For hemodynamic improvement
To prevent tachyarrhythmias

42. Indications for artificial cardiac pacing in AV block
Pacemaker necessary
Symptomatic or asymptomatic acquired CHB
Symptomatic congenital CHB
Atrial fibrillation with CHB
Symptomatic second degree Mobitz type I or type II block

43. Indications for artificial cardiac pacing in AV block
Pacemaker probably necessary:
Asymptomatic Mobitz type II block
Asymptomatic Mobitz type I block at intra His or infra His level
Hemodynamically symptomatic first degree block (due to loss of AV synchrony)

44. Indications for artificial cardiac pacing in AV block
Pacemaker not necessary :
Asymptomatic Mobitz type I at supra His level
Asymptomatic first degree block

45. red - Pacemaker necessary blue- Pacemaker probably necessary green- Pacemaker not necessary
Symptomatic third degree
Asymptomatic third degree
Symptomatic 2nd degree type 2
Symptomatic 2nd degree type 1
Asymptomatic 2nd degree type 2
Asymptomatic 2nd deg type 1(infra His)
Asymptomatic 2nd deg type 1(supra His)
Symptomatic 1st deg
Asymptomatic 1st deg

46. Fascicular block Pacemaker necessary:
Bi- or tri- fascicular block associated with CHB (symptomatic or not)
Associated with intermittent Mobitz type II block

47. Fascicular block Pacemaker probably necessary:
Bi or tri fascicular block with syncope
HV interval more than 100 ms

48. Fascicular block Pacemaker not necessary :
Fascicular block without AV block without symptoms

49. Sinus node dysfunction
Pacemaker necessary:
Symptomatic sinus bradycardia including frequent sinus pauses
Symptomatic sinus bradycardia due to long term drug therapy of a type and at a dose for which there is no accepted alternative

50. Sinus node dysfunction
Pacemaker probably necessary:
Symptomatic patients with SND with documented rates less than 40 bpm without clear cut association between symptoms and bradycardia

51. Sinus node dysfunction
Pacemaker not necessary :
Asymptomatic SND
Asymptomatic bradycardia due to drug therapy

52. Neurocardiogenic syncope
Due to carotid sinus hypersensitivity and vasovagal syncope
Recurrent syncope caused by carotid sinus stimulation and minimal pressure induce asystole of more than 3 sec in the absence of any medication that depresses conduction

53. Pacing for hemodynamic improvement
Hypertrophic cardiomyopathy
Dilated cardiomyopathy
Congestive cardiac failure
Atrial fibrillation
Sequential pacing to avoid pacemaker syndrome

54. HOCM Medically refractory and severely symptomatic HOCM
Dual chamber pacing - right atria and right ventricle
Altered septal activation by right ventricular apical pacing causes less narrowing of LVOT
Permanent pacing can lead to long term remodelling of LV

55. DCM
AV sequential pacing
Biventricular pacing

56. AF
Dual site atrial pacing has been used to prevent recurrent atrial tachyarrhythmias

57. Indications for temporary pacing
Sinus bradycardia or lower escape rhythm due to reversible cause with symptoms of hemodynamic compromise
As standby in patients with increased risk of sudden high degree AV heart block
Bridge to permanent pacing in 2nd or 3rd degree AVHB
During AMI: asystole, new bifascicular block, symptomatic bradycardia not responsive to drugs, Mobitz type II
Bradycardia dependent tachydysrhythmia (TDS with LQTS)

58. Indications for temporary pacing
During and after heart surgery for :
To overdrive hemodynamically disadvantageous junctional and ventricular rhythm
Terminate SVT or VT
Prevent bradycardia dependent tachydysrhythmias

59. Trans venous pacing Temporary or permanent
Subclavian or cephalic vein preferred

60. Temporary transvenous pacing – external controls
VVI/VVO
Output (mA)
Rate
R wave sensitivity (mV)
DVI
Output (mA) ventricular
Output (mA) atrial
Rate
R wave sensitivity (mV)
AVI

61. Trans cutaneous pacing
Position of electrodes
V3 (negative)
Left of spine at the lower aspect of scapula (positive)
Pulse duration ms
Threshold – mA

62. Trans esophageal pacing
Mostly leads to atrial capture
Electrodes can be placed 1.5 cm from the left atrium
An intact AV conduction pathway is essential

63. Epicardial placement Not preferred route
Mostly used after cardiac surgery
Only preferred when no access to right ventricle:
Associated congenital anomaly
Prosthetic tricuspid valve
Intra cardiac right to left shunt

64. Nomenclature of Implantable Cardioverter Defibrillator (ICD)
Position I
(shock chamber)
O- none
A- atrium
V- ventricle
D- dual (atrium and ventricle)
Position II
(anti tachycardia pacing chamber)
O- none
A- atrium
V- ventricle
D- dual (atrium and ventricle)

65. Nomenclature of ICD Position III
(method of detection of tachyarrhythmia)
E- intracardiac electrogram
H- hemodynamic means
Three of five letter code for pacemaker capability of device

66. Indications for ICD
Cardiac arrest due to VF or VT not due to transient or reversible cause
Spontaneous sustained VT
Nonsustained VT with CAD, prior MI, LV dysfunction and inducible VF or sustained VT at EPS
Syncope of undetermined origin with hemodynamically significant VF or VT at EPS.

67. ICD may be indicated in Cardiac arrest presumed due to VF/VT
Severely symptomatic VT before cardiac transplantation
LQTS, HCM – high risk of lifethreatening ventricular dysrhythmias

68. To be continued by Dr. Bala